Electrophysiology catheters are commonly-used for mapping electrical activity in the heart. Various electrode designs are known for different purposes. In particular, catheters having basket-shaped electrode arrays are known and described, for example, in U.S. Pat. Nos. 5,772,590, 6,748,255 and 6,973,340, the entire disclosures of both of which are incorporated herein by reference.
Basket catheters typically have an elongated catheter body and a basket-shaped electrode assembly mounted at the distal end of the catheter body. The basket assembly has proximal and distal ends and comprises a plurality of spines connected at their proximal and distal ends. Each spine comprises at least one electrode. The basket assembly has an expanded arrangement wherein the spines bow radially outwardly and a collapsed arrangement wherein the spines are arranged generally along the axis of the catheter body. The catheter may further comprise a distal location sensor mounted at or near the distal end of the basket-shaped electrode assembly and a proximal location sensor mounted at or near the proximal end of the basket-shaped electrode assembly. In use, the coordinates of the distal location sensor relative to those of the proximal sensor can be determined and taken together with known information pertaining to the curvature of the spines of the basket-shaped mapping assembly to find the positions of the at least one electrode of each spine.
It is desirable that a basket assembly be capable of detecting in a single beat most or all of the electrical function of the left or right atrium. However, because the atria of an individual patient may vary in size and shape, it is desirable that the basket assembly be sufficiently versatile and steerable to conform to the particular atrium. Conventional basket catheters have an intermediate deflectable section that is proximal of the basket assembly, but the basket assembly itself is typically without steerability or deflectability. As such, the basket assembly often lacks sufficient maneuverability and stability to provide useful contract with enough atrial tissue at any in any single instance. Accordingly it is desirable that a catheter have a basket assembly with improved maneuverability for better tissue contact, especially in a cavernous region of the heart, including an atrium.